Cable for communication circuits



Feb. 28, 1933. w. GABRIEL. 1,399,501

CABLE FOR COMMUNICATION CIRCUITS Filed June 27, 1930 Patented Feb. 28, .1933

UNITED sures PATENT OFFICE WILHELI GABRIEL, 0I" BERLIN-SPANDAU, GERMANY, ASSIGNOR TO SIEMENS k HALSKE, AKTIENGESELLSCHAIT, OI SIEIENSSTADT NEAR BERLIN, GERMANY, A

CORPORATION 01 GERMANY cum: roa oonnumcil'rloinomcurrs Application filed June 37, 1880, Serial 1!o.'484,808, andjn Qermany July 5, 1829.

My invention relates to cables for communication circuits, hereafter called communication cables; and particularly to cables of this kind, in which the inductance is uniformly distributed. In order to obtain a un1- form distribution of the inductance in Krarup cables, the individual conductors of the cable are, as is known, covered all along withone or more layers of wires, bands, or the like, of magnetic material. As the kinds of iron hitherto available possess only a relatively small permeability and have hi h iron losses, it was only possible to obtain a imited increase in inductance and, therefore, only a limited reduction in the dampin in cables of that kind. It was, consequenti y, hitherto not possible to employ that kind of cable for bridging distances considerably over 200 kilometres. Although it has recently become possible to produce highly ermeable ma netic alloys, alloys of iron with nickel, stil these alloys alone are but to a small degree suitable for increasing the inductance of the communication cables, as their permeability is not constant at different current intensities but is to a high degree dependent upon the current intensity.

In order to be able to employ communication cables with uniformly distributed inductance for very long distances, the conductorsare, according to the invention, covered with several magnetic layers in such a manner that the permeability of the covering is as high as possible and at the same time as constant as possible at difi'erent current intensities. The rmeability of a material being generally a l the more constant the lower the permeability, and being all the less constant the higher the permeability, magnetic layers having a high constancy at a low permeabi ity, are, according to experience, arranged close to the conductor, where the magnetizing forces are the strongest, whilst further away, where the magnetizing forces are weaker, layers are placed, the permeability of which is lessconstant but very high.

=As magnetic layers of high constancy at a low permeability, steel, iron or alloys of iron with a. high iron content are preferably used. For the magnetic layers of high permeability but of relatively poor constancy, highly permeable alloys, for example, 'permalloy are suitably employed. By this means a comparatively large and at the same-time a comparati ely constant mean permeability is ob-- tained for a wide range of current intensities, whereby the damping is considerably reduced and the possibility given of bridging large distances.

,To obtain a greater constancy in the permeability also in the outer layers, consisting of highly permeable alloys, the latter layers may in. known manner be wound with a larger pitch so that air spaces are left between the Individual windings. By doing so, the permeability is, however, somewhat reduced. It is also possible to apply the inner layers of lesser permeability in the form of powder, and to employ wires or bands for the outer layers of high permeability. In many cases,

it is sufficient to apply the arrangement according to the invention only at the ends of the cable.

In the drawings several practical forms of the invention are illustrated as examples, Fig. 1 representing a cable portion having an inner winding of material of low, but constant permeability, and an outer winding of less constant but high permeability;'Fig. 2 representing a. cable portion having an inner layer of powder of low, but constant permeability and an outer ribbon winding of less constant but high'permeability; and Fig. 3 representing a cable portion similar to Fig. 2, excepting the provision of a very close outer wire windin Referring to Fig. 1, 2 is a conductor of a cable. upon which a closely wound winding 3, consisting of a material having a "cry constant but rather low permeability is placed, over which a winding 4. consisting of a band of material, having a high magnetic permeability of less constancy, is wound as an open spiral.

In Fig. 2 the uniformly distributed high inductivity is attained by surrounding the conductor 12 first with a material 13 of low but constant permeability in powder form. The manner of applying the coating of pow-' der may be for instance that suggested in the U. S. Patent 1,672,979 of June 12, 1928. Upon this coating is then wound a wide ribbon material 14 of less constant but high permeability.

In Fig. 3 the powder coating-23 immediately surrounding conductor 22 may be the same as in Fig. 2, but the outer layer consists in this case of a wire of less constant but high'permeability wound very closely.

- I clairri a s my invention:

. 1. A conductor for communication cables with uniformly distributed inductance, having magnetiza le material placed upon it in at least two layers. the inner layer consisting of magnetizable material of low but constant permeability, the outer layer'consisting of magnetizable material of highbut less constant permeability.

2. A conductor for communication cables with uniformly distributed inductance, having magnetizable material placed upon it in at least two layers, the inner layerconsisting of magnetizable material of low but constant permeability and being applied in the form of powder, the outer layer consisting of magnet zable material of high but less constant permeabilit wound upon the powder layer.

3. A conductor for communication cables with uniformly distributed inductance, having magnetizable material placed upon it in at least two layers, the inner layer consisting of magnetizable material of low but constant permeability and being applied in the form of powder, the outer layer consist ng of magnetizable ribbon material of high but less constant permeability wound upon the powder layer.

A conductor for communication cables with uniformly distributed inductance, having magnetizable material placed upon it in at least two layers, the inner layer consisting of magnetizable wire material of low but constant permeability wound upon the conductor, the outer layer consisting of magnetizable ribbon material of high but less concation cables having at least two la ers of magnetizable material placed upon t e conductor, said layers having opposite magnetic characteristics with respect to constancy and degree of permeability, to complement one another in said characteristics, whereby a conductor inductance uniformly distributed over great distances is produced.

In testimony whereof I aflix my signature.

VVILHELM GABRIEL.

stant permeability wound upon the wire layer at a greater pitch than the wire layer.

5. A conductor for communication cables with uniformly distributed inductance. having magnetizable material placed upon it in at least two layers, the inner layer consisting of iron wire closely wound upon the conductor. the outer layer consisting of a ribbon of a highly permeable alloy wound upon the wire layer in an open spiral.

6. A conductor for long distance communication cables. having' a plurality of layers of magnetizable material placed upon the conductor. successive layers having 'opposite magnetic characteristics with respect to constancy and degree of permeability, to complement one another in said characteristics, whereby a conductor in'ductance uniformly diatributed yer great distances is produced.

'7 A conductor for longdistance communi- 

